Geometry.java

enum GeometryType { POINT, MULTIPOINT, POLYLINE, POLYGON }

abstract class Geometry {
  GeometryType geometryType;
  
  Geometry(GeometryType geometryType) {
    this.geometryType = geometryType;
  }
}

class Point extends Geometry {
  double x;
  double y;
  
  Point(double x, double y) {
    super(GeometryType.POINT);
    this.x = x;
    this.y = y;
  }
}

class Multipoint extends Geometry { /* ... */ }
class Polyline extends Geometry { /* ... */ }
class Polygon extends Geometry { /* ... */ }

InstanceOf.java

if (geometry instanceof Point) {
  /* ... */
} else if (geometry instanceof Multipoint) {
  /* ... */
} else if (geometry instanceof Polyline) {
  /* ... */
} else if (geometry instanceof Polygon) {
  /* ... */
}

Switch.java

switch (geometry.geometryType) {
  case POINT:
    /* ... */
    break;
  case MULTIPOINT:
    /* ... */
    break;
  case POLYLINE:
    /* ... */
    break;
  case POLYGON:
    /* ... */
    break;
}